and the unclassified stuff is wildly uninteresting
Woah, woah woah. Inaccurate assumptions everywhere.
First, those interviewing you aren't trying to simple suffer through an interview and be entertained. They are trying to figure out whether you would make a quality employee and fit their team. Your primary job as the interviewee is not to simply tell entertaining stories for most interviews.
Second, there is always something in every project worth discussing (unless you literally worked on nothing). Find these and discuss these. It is impossible to have literally nothing worth talking about when you work on teams, have deliverables, have to learn, work on technical projects, or have any sort of interaction with people - this tends to cause conflict regardless as to whether it's classified or not. The majority of this is 100% independent of the details of your assignments.
This means you can still answer nearly every behavioral question which you are presented with without discussing a single detail of your classified information.
For example, compare the following:
- "I had to work with Brett Spiner on the implementation of a warp plasma drive using C++ and the Trek framework, but we had some serious issues implementing the Picard method - this caused us to need help, but problems with the Borg stopped us from getting it implemented correctly and we had to use a SuperSecritTechnology card to get it fixed. Brett and I had some real problems with communication because he was a prototype secret android and we had to work through those issues by reprogramming him in SuperSecritTechnology."
- "I was working on a project which was highly technical, using a classified framework - we ran into some problems with communication during an implementation problem. This required us to spend some serious time working through these issues, which we found resulted from our unique ways of seeing the world"
Both communicate the same ability - being able to handle communication problems. One is considerably more generic.
Third, if your resume has enough information to get you interviews, your skill-set is clearly generic enough to be able to not hide this due to your classified work experience part. What are you telling people? "I'm a java developer but I can't talk about my java skills because they are classified?"
I usually just tell the interviewer that "unfortunately, my professional experience is classified"
"While the specifics of most of my professional experience are classified, I would love to talk through as much as possible in a more general sense for some of the challenges and experiences I have. I will let you know if I cannot give more details because they are classified to a question - feel free to ask clarifications and I will do my best!"
edit to add - I guess I was assuming you have done this but make sure you speak with your manager from the contract positions about how to handle this work in interviews. If you've not done this, this is Step 0. Also read through any documents you have on this subject (again, assuming you've already done this).